1. Field of the Invention
The invention relates to an arrangement in a circulation lubrication system, and more specifically to an arrangement comprising control means for controlling, in a desired manner, the flow of lubricating oil supplied to a part to be lubricated.
2. Description of Related Art
The above-described circulation lubrication systems are quite well-known today in various fields of the industry. In circulation lubrication systems, the lubricating oil is pumped out of a lubricant tank, through pipe lines, to the parts to be lubricated, and returned by means of return pipe lines to the lubricant tank. In circulation lubrication system, the oil typically has a constant pressure, which is about 5 bar. The flow is passed to the parts to be lubricated by means of separate flow meters. The oil flow control in the flow meters is typically carried out by using a throttle control, in which the desired flow to the parts to be lubricated is achieved by changing the cross-sectional area of the flow. In a typical known solution, the cross-sectional area of the flow is changed by means of a mechanism operated with an adjusting screw to the effect that when the adjusting screw is turned outwards, the cross-sectional area of the flow becomes larger and the flow increases. When the adjusting screw is turned inwards, the cross-sectional area of the flow becomes smaller and the flow decreases.
One drawback of the prior art solution is, for instance, that the control acts on the flow very quickly. At their lowest, flow rates to be controlled are in the range of 0.02 l/min, and thus the accurate control is achieved only with great difficulty by using the throttle control that acts in the above-mentioned manner, unless the whole operating range of the control device is reduced, for instance, to a ratio of 1/100, permitting the control device to control, at the maximum, the flow of 2 liters per minute. This adjustment range is then to be controlled with approximately ten round turns of the adjusting screw. One more drawback is that, during the adjustment, the movement of the adjusting screw is directed outwards from the body of the meter or inwards to the body of the meter, depending on the control direction, which makes the motorization of the control difficult. The above solution further increases the total length of the control device, and a tool is always needed for carrying out an adjustment.